Missing top layers when spiral atop surface

[keith20mm 0]

I have a chuck scroll plate, which is a rectangular cross section spiraling from center out.

 

I have Top Layers 3, with layer thickness 0.2.

 

The top layers atop the upper face on the scroll plate, upon which sits the spiral, were omitted in the slice.  If you inspect the photo, you can clearly see the exposed infill, lacking top layers, meanwhile, the spiral continues to be laid down.

 

Why???

ScrollPlateB.gcode ScrollPlateB.3mf ScrollPlateB.stl

[keith20mm 0]

Ignore all commentary on this non-bug report.

 

Consider it bad focus and double vision.  Cura is working correctly.